LXR linux/include/linux/netlink.h

   1/* SPDX-License-Identifier: GPL-2.0 */
   2#ifndef __LINUX_NETLINK_H
   3#define __LINUX_NETLINK_H
   4
   5
   6#include <linux/capability.h>
   7#include <linux/skbuff.h>
   8#include <linux/export.h>
   9#include <net/scm.h>
  10#include <uapi/linux/netlink.h>
  11
  12struct net;
  13
  14void do_trace_netlink_extack(const char *msg);
  15
  16static inline struct nlmsghdr *nlmsg_hdr(const struct sk_buff *skb)
  17{
  18        return (struct nlmsghdr *)skb->data;
  19}
  20
  21enum netlink_skb_flags {
  22        NETLINK_SKB_DST         = 0x8,  /* Dst set in sendto or sendmsg */
  23};
  24
  25struct netlink_skb_parms {
  26        struct scm_creds        creds;          /* Skb credentials      */
  27        __u32                   portid;
  28        __u32                   dst_group;
  29        __u32                   flags;
  30        struct sock             *sk;
  31        bool                    nsid_is_set;
  32        int                     nsid;
  33};
  34
  35#define NETLINK_CB(skb)         (*(struct netlink_skb_parms*)&((skb)->cb))
  36#define NETLINK_CREDS(skb)      (&NETLINK_CB((skb)).creds)
  37
  38
  39void netlink_table_grab(void);
  40void netlink_table_ungrab(void);
  41
  42#define NL_CFG_F_NONROOT_RECV   (1 << 0)
  43#define NL_CFG_F_NONROOT_SEND   (1 << 1)
  44
  45/* optional Netlink kernel configuration parameters */
  46struct netlink_kernel_cfg {
  47        unsigned int    groups;
  48        unsigned int    flags;
  49        void            (*input)(struct sk_buff *skb);
  50        struct mutex    *cb_mutex;
  51        int             (*bind)(struct net *net, int group);
  52        void            (*unbind)(struct net *net, int group);
  53        bool            (*compare)(struct net *net, struct sock *sk);
  54};
  55
  56struct sock *__netlink_kernel_create(struct net *net, int unit,
  57                                            struct module *module,
  58                                            struct netlink_kernel_cfg *cfg);
  59static inline struct sock *
  60netlink_kernel_create(struct net *net, int unit, struct netlink_kernel_cfg *cfg)
  61{
  62        return __netlink_kernel_create(net, unit, THIS_MODULE, cfg);
  63}
  64
  65/* this can be increased when necessary - don't expose to userland */
  66#define NETLINK_MAX_COOKIE_LEN  20
  67
  68/**
  69 * struct netlink_ext_ack - netlink extended ACK report struct
  70 * @_msg: message string to report - don't access directly, use
  71 *      %NL_SET_ERR_MSG
  72 * @bad_attr: attribute with error
  73 * @policy: policy for a bad attribute
  74 * @cookie: cookie data to return to userspace (for success)
  75 * @cookie_len: actual cookie data length
  76 */
  77struct netlink_ext_ack {
  78        const char *_msg;
  79        const struct nlattr *bad_attr;
  80        const struct nla_policy *policy;
  81        u8 cookie[NETLINK_MAX_COOKIE_LEN];
  82        u8 cookie_len;
  83};
  84
  85/* Always use this macro, this allows later putting the
  86 * message into a separate section or such for things
  87 * like translation or listing all possible messages.
  88 * Currently string formatting is not supported (due
  89 * to the lack of an output buffer.)
  90 */
  91#define NL_SET_ERR_MSG(extack, msg) do {                \
  92        static const char __msg[] = msg;                \
  93        struct netlink_ext_ack *__extack = (extack);    \
  94                                                        \
  95        do_trace_netlink_extack(__msg);                 \
  96                                                        \
  97        if (__extack)                                   \
  98                __extack->_msg = __msg;                 \
  99} while (0)
 100
 101#define NL_SET_ERR_MSG_MOD(extack, msg)                 \
 102        NL_SET_ERR_MSG((extack), KBUILD_MODNAME ": " msg)
 103
 104#define NL_SET_BAD_ATTR_POLICY(extack, attr, pol) do {  \
 105        if ((extack)) {                                 \
 106                (extack)->bad_attr = (attr);            \
 107                (extack)->policy = (pol);               \
 108        }                                               \
 109} while (0)
 110
 111#define NL_SET_BAD_ATTR(extack, attr) NL_SET_BAD_ATTR_POLICY(extack, attr, NULL)
 112
 113#define NL_SET_ERR_MSG_ATTR_POL(extack, attr, pol, msg) do {    \
 114        static const char __msg[] = msg;                        \
 115        struct netlink_ext_ack *__extack = (extack);            \
 116                                                                \
 117        do_trace_netlink_extack(__msg);                         \
 118                                                                \
 119        if (__extack) {                                         \
 120                __extack->_msg = __msg;                         \
 121                __extack->bad_attr = (attr);                    \
 122                __extack->policy = (pol);                       \
 123        }                                                       \
 124} while (0)
 125
 126#define NL_SET_ERR_MSG_ATTR(extack, attr, msg)          \
 127        NL_SET_ERR_MSG_ATTR_POL(extack, attr, NULL, msg)
 128
 129static inline void nl_set_extack_cookie_u64(struct netlink_ext_ack *extack,
 130                                            u64 cookie)
 131{
 132        if (!extack)
 133                return;
 134        memcpy(extack->cookie, &cookie, sizeof(cookie));
 135        extack->cookie_len = sizeof(cookie);
 136}
 137
 138static inline void nl_set_extack_cookie_u32(struct netlink_ext_ack *extack,
 139                                            u32 cookie)
 140{
 141        if (!extack)
 142                return;
 143        memcpy(extack->cookie, &cookie, sizeof(cookie));
 144        extack->cookie_len = sizeof(cookie);
 145}
 146
 147void netlink_kernel_release(struct sock *sk);
 148int __netlink_change_ngroups(struct sock *sk, unsigned int groups);
 149int netlink_change_ngroups(struct sock *sk, unsigned int groups);
 150void __netlink_clear_multicast_users(struct sock *sk, unsigned int group);
 151void netlink_ack(struct sk_buff *in_skb, struct nlmsghdr *nlh, int err,
 152                 const struct netlink_ext_ack *extack);
 153int netlink_has_listeners(struct sock *sk, unsigned int group);
 154bool netlink_strict_get_check(struct sk_buff *skb);
 155
 156int netlink_unicast(struct sock *ssk, struct sk_buff *skb, __u32 portid, int nonblock);
 157int netlink_broadcast(struct sock *ssk, struct sk_buff *skb, __u32 portid,
 158                      __u32 group, gfp_t allocation);
 159int netlink_broadcast_filtered(struct sock *ssk, struct sk_buff *skb,
 160                               __u32 portid, __u32 group, gfp_t allocation,
 161                               int (*filter)(struct sock *dsk, struct sk_buff *skb, void *data),
 162                               void *filter_data);
 163int netlink_set_err(struct sock *ssk, __u32 portid, __u32 group, int code);
 164int netlink_register_notifier(struct notifier_block *nb);
 165int netlink_unregister_notifier(struct notifier_block *nb);
 166
 167/* finegrained unicast helpers: */
 168struct sock *netlink_getsockbyfilp(struct file *filp);
 169int netlink_attachskb(struct sock *sk, struct sk_buff *skb,
 170                      long *timeo, struct sock *ssk);
 171void netlink_detachskb(struct sock *sk, struct sk_buff *skb);
 172int netlink_sendskb(struct sock *sk, struct sk_buff *skb);
 173
 174static inline struct sk_buff *
 175netlink_skb_clone(struct sk_buff *skb, gfp_t gfp_mask)
 176{
 177        struct sk_buff *nskb;
 178
 179        nskb = skb_clone(skb, gfp_mask);
 180        if (!nskb)
 181                return NULL;
 182
 183        /* This is a large skb, set destructor callback to release head */
 184        if (is_vmalloc_addr(skb->head))
 185                nskb->destructor = skb->destructor;
 186
 187        return nskb;
 188}
 189
 190/*
 191 *      skb should fit one page. This choice is good for headerless malloc.
 192 *      But we should limit to 8K so that userspace does not have to
 193 *      use enormous buffer sizes on recvmsg() calls just to avoid
 194 *      MSG_TRUNC when PAGE_SIZE is very large.
 195 */
 196#if PAGE_SIZE < 8192UL
 197#define NLMSG_GOODSIZE  SKB_WITH_OVERHEAD(PAGE_SIZE)
 198#else
 199#define NLMSG_GOODSIZE  SKB_WITH_OVERHEAD(8192UL)
 200#endif
 201
 202#define NLMSG_DEFAULT_SIZE (NLMSG_GOODSIZE - NLMSG_HDRLEN)
 203
 204
 205struct netlink_callback {
 206        struct sk_buff          *skb;
 207        const struct nlmsghdr   *nlh;
 208        int                     (*dump)(struct sk_buff * skb,
 209                                        struct netlink_callback *cb);
 210        int                     (*done)(struct netlink_callback *cb);
 211        void                    *data;
 212        /* the module that dump function belong to */
 213        struct module           *module;
 214        struct netlink_ext_ack  *extack;
 215        u16                     family;
 216        u16                     answer_flags;
 217        u32                     min_dump_alloc;
 218        unsigned int            prev_seq, seq;
 219        bool                    strict_check;
 220        union {
 221                u8              ctx[48];
 222
 223                /* args is deprecated. Cast a struct over ctx instead
 224                 * for proper type safety.
 225                 */
 226                long            args[6];
 227        };
 228};
 229
 230struct netlink_notify {
 231        struct net *net;
 232        u32 portid;
 233        int protocol;
 234};
 235
 236struct nlmsghdr *
 237__nlmsg_put(struct sk_buff *skb, u32 portid, u32 seq, int type, int len, int flags);
 238
 239struct netlink_dump_control {
 240        int (*start)(struct netlink_callback *);
 241        int (*dump)(struct sk_buff *skb, struct netlink_callback *);
 242        int (*done)(struct netlink_callback *);
 243        void *data;
 244        struct module *module;
 245        u32 min_dump_alloc;
 246};
 247
 248int __netlink_dump_start(struct sock *ssk, struct sk_buff *skb,
 249                                const struct nlmsghdr *nlh,
 250                                struct netlink_dump_control *control);
 251static inline int netlink_dump_start(struct sock *ssk, struct sk_buff *skb,
 252                                     const struct nlmsghdr *nlh,
 253                                     struct netlink_dump_control *control)
 254{
 255        if (!control->module)
 256                control->module = THIS_MODULE;
 257
 258        return __netlink_dump_start(ssk, skb, nlh, control);
 259}
 260
 261struct netlink_tap {
 262        struct net_device *dev;
 263        struct module *module;
 264        struct list_head list;
 265};
 266
 267int netlink_add_tap(struct netlink_tap *nt);
 268int netlink_remove_tap(struct netlink_tap *nt);
 269
 270bool __netlink_ns_capable(const struct netlink_skb_parms *nsp,
 271                          struct user_namespace *ns, int cap);
 272bool netlink_ns_capable(const struct sk_buff *skb,
 273                        struct user_namespace *ns, int cap);
 274bool netlink_capable(const struct sk_buff *skb, int cap);
 275bool netlink_net_capable(const struct sk_buff *skb, int cap);
 276
 277#endif  /* __LINUX_NETLINK_H */
 278